In article <DeAqc.50527$325.1090290 at news20.bellglobal.com>,
"NMF" <nm_fournier at ns.sympatico.ca> wrote:
> So the process you have mentioned suggests that the temporal coding of BAP
> and EPSP has been likened to the important coincidence detector that Hebb
> remarked in his work. The spike-dependent (Hebbian plasticity) process is
> considered important for producing long lasting changes in synaptic
> potentation. Moreover, due to the rather compartmentalized aspect of the
> dendritic tree (i.e. branches, necks, spines, and complex geometry of
> dendrites), one would find the potential for many different local
> coincidence detection mechanisms, i.e. the NMDA receptor, itself, or even
> the ryanodine-sensitive internal stores might all serve as coincidence
> detection apparatus.
Neil, sounds like you have also read (or ought to read) the work of Greg
Stuart and Michael Hausser regarding the immense complexity of synaptic
inputs filtering through a dendritic tree. Not only do large changes in
membrane capacitance cause great variation in EPSP (more distal = larger
in general, for a given current), but the generation of sodium and
calcium spikes which are actively propagated is a very strong
coincidence detection mechanism, although the coincidence would need to
be between two inputs rather than a pre and postsynaptic cell. Of
course the BAP gets into this melee as well. I love telling students
this stuff when they think they have neuron basics down pat. Then when
they get comfortable there, I hit them with glial interactions. I
always say, if it seems straightforward, you haven't understood the
problem!
Cheers,
Matthew.